Boom construction for a mechanical excavator



March 1955 N. BROCKLEBANK ETAL 3,173,551

BOOM CONSTRUCTION FOR A MECHANICAL. EXCAVATOR Filed Aug. 26, 196-3 4Sheets-$heet 1 Inventors /V Brock/elven G Scot f Attorneys March 1965 N.BROCKLEBANK ETAL 3,173,561

BOOM CONSTRUCTION FOR A MECHANICAL EXCAVATOR Filed Aug. 26, 1963 4Sheets-Sheet 2 Invenlors /V, 5 rock/962M144 G. sco't March 15, 1955 N.BROCKLEBANK ETAL 3,173,551

BOOM CONSTRUCTION FOR A MECHANICAL EXCAVATOR Filed Aug. 26, 1963 4Sheets-Sheet I5 Mamh 1965 N. BROCKLEBANK ETAL 3,173,561

BOOM CONSTRUCTION FOR A MECHANICAL. EXCAVATOR Filed Aug. 26, 1965 4Sheets-Sheet 4 By kw Wrney 3 United States Patent 3,173,561 BOOMCONSTRUCTION FOR A MECHANICAL EXCAVATOR Norman Brocklebank, New Walk,Beverley, and Gordon Scott, Hull, England, assignors to PriestrnanBrothers Limited, Yorkshire, England, a British company Filed Aug. 26,1963, Ser. No. 304,585 Claims priority, application Great Britain, Aug.28, 1962, 33,005/ 62 Claims. (Cl. 214-138) This invention relates tohydraulically operated excavators, such as drag shovels and faceshowels, of the kind which have a boom and an arm pivoted together witha digging bucket mounted on the outer end of the arm. The boom and thearm are rocked relatively to each other and the bucket may be rocked onthe outer end of the arm by means of hydraulic rams.

When a drag shovel of this kind is used for digging a trench, it iscustomary for the machine to stand in line with the trench and movebackwards as it digs the trench towards itself. It is difiiculttherefore to use a conventional drag shovel for excavating a trenchwhich is very close to a wall or other construction because there is notroom for the machine to align itself with the trench. Similar problemsarise when using a conventional face shovel in a similar position.

According to the present invention the boom of such an excavator is intwo pants which are detachably fixed together by a mounting which allowsthe outer part to slew from side to side relatively to the inner partand to be fixed to the inner part in any one of three differentpositions, in the first of which the two parts of the boom are alignedwith each other so that the axis of the boom is straight as seen fromabove, and in the other two of which the outer part of the boom is setat an angle laterally as seen from above to the inner part of the boom,the outer part being offset in opposite directions in these twopositions.

When the two parts of the boom are fixed together in the first position,that is to say with the whole boom straight, the evcavator can be usedin the usual way. Thus if the excavator is a drag shovel it can be usedin line with the trench which it is digging. However the arrangementenables the machine to dig a trench parallel and close to an obstructionsuch as a wall by slewing the superstructure of the machine in one senseon the chassis of the machine and slewing the outer upper part of theboom in the other sense relatively to the inner lower part of the boomand locking the two parts together in this relative position. When thisis done the vertical plane containing the outer part of the boom islaterally offset from the central longitudinal line of the chassis sothat a trench can be dug which is in line with the side edge of or evenoutside the wheel base of the chassis.

Preferably, the means for connecting the two parts of the boom to oneanother comprises a pivot pin which passes through tubular sockets inthe two parts of the boom. The outer part of the boom can then swingrelatively to the inner part about this pivot pin and can be fixed inany one of the three positions by bolts which pass through both parts ofthe boom. The boom pants are preferably steel plate box girderconstruction.

As well as being arranged to slew relatively to one another, the twoparts of the boom may also be arranged telescopically as described inour co-pending application No. 304,586, filed August 26, 1962. In thiscase the two parts of the boom will be able to slew relatively to oneanother only when the boom is in its extended position.

One example of an excavator constructed in accordance 3,173,561 PatentedMar. 16, 1965 with the present invention is illustrated in theaccompanying drawings, in which:

FIGURE I is a side elevation;

FIGURE 11 is a plan showing the excavator digging a trench in line withthe right hand edge of its tracks;

FIGURE III is a side elevation of the boom per se with the outer partshown in one lateral position relative to the inner part;

FIGURE IV is a plan of the boom as shown in FIG- URE III;

FIGURE V is an enlarged plan of the connection between the two boompants when they are aligned with one another;

FIGURE VI is a section taken on the lines VIVI in FIGURE IV;

FIGURE VII is a section taken on the line VII-VII in FIGURE IV; and,

FIGURE VIII is a section of the inner boom part only taken on the lineVIII-VIII in FIGURE IV.

FIGURE IX is a section taken on the line IX-IX of FIGURE IV.

The excavator, which is the same machine as that illustrated anddescribed in our copending applicatlon No. 304,586 filed August 26,1962, consists of a superstructure 1 which is carried through aturntable 2 on a track laying chassis 3. An inner part 4 of a steelplated box shaped boom is pivoted at its lower end to a bracket 5 of thesuperstructure 1. The boom can be raised and lowered by means of a pairof hydraulic rams 6 which extend between lugs 7 on the superstructure 1and lugs 8 at the outer end of the inner boom art 4. P The upper orouter part of the boom 9, which can telescope within the inner boom part4, is arranged when extended to slew relatively to the inner part 4 andto be fixed in any one of three different positions relatively to theinner part 4. A digging arm 10 having a plate 11 at each side is pivotedby means of the brackets at 12 to the upper end of the boom part 9 toenable the digging arm 10 to swing backwards and forwards on the upperend of the boom. This swinging movement is controlled by a hydraulic ram13 one end of which is anchored between lugs 14 on the inner end of theouter boom part 9 and the other end of which is anchored to a bracket 15carried between the plates 11. A digging bucket 16 is pivotally mountedon the outer end of the arm 10 and can be rocked backwards and forwardson the end of the arm by a hydraulic ram 17. One end of the ram 17 isanchored to the plates 11 and the other end is connected to flanges 18on the back of the bucket through a swivel link 19. The bucket has twoalternative connections 20 and 21 by either of which it can be connectedto the end of the arm 10. The arrangement is such that the bucket can bedisconnected from the end of the arm 10, swung around through on theswivel 19 and reconnected by the other connection 20 or 21 to the arm10. In this way the excavator can be converted from a drag shovel orback-actor to a face shovel and vice versa easily. This arrangement isfully described and claimed in our copending application No 294,658filed July 12, 1963.

The construction of the two boom parts 4 and 9 which enables the outerpart 9 to slew relatively to the inner part and to telescope into theinner part is shown most clearly in FIGURES III to VIII. The inner boompart 4 consists of two box sections 22 arranged side by side andconnected by .a bottom plate 23 which is welded to them. The two boxsections increase in depth from a minimum at the inner end to a maximuma short dis tance away from the outer end. The inner boom part istherefore substantially U-shaped in section and the outer and beneathinturned lips 23a on the inner walls of thebox sections. These innerwalls of the box sections 22 extend above the sections asthey taper. ina direction towards the inner end of the boom to provide a channel ofconstant height to receive the inner end of the outer boom parts as ittelescopes within the inner part. At their extreme inner ends, theboxisections 22 terminate in tubular sockets 24 for receiving the pivotpin which connects the inner end of the boom to the bracket 5.

At its extreme outer end, the boom part 4 is strengthened with upper.and lower plates 25 and 26 respectively which define between them anenlarged housing 27 which enables the extreme inner end of the outerpart 9 to move from side to side when the outer boom part 9 is slewedrelatively to the inner part 4. The bottom plate 26 extends across therun width of the boom 'but the upper plate has its centre and rearportion cut away to provide access to the housing 27. The lugs 8 for therams 6 are welded to the top plate 25..

The outer boom part 9 is also of boxconstruction and.

consists of four plates welded together at each corner of the section.There is .a portion 28 of constant height at the inner end of the boompart 9 but beyond this the rest of the boom part tapers towards itsouter end. At its extreme outer end the part '9 is formed with a tubularsocket 29 for receiving a pivot pin which connects the plate brackets 11to theen'd of the boom.

Adjacent its inner end the outer boom part9 is formed with a tubularsocket 30 and adjacent its outer end it is formed with another tubularsocket 31 of similar shape and size to the first. The socket 31 'issupported by a Web 32 where it'projects above the tapering boxsection ofthe boom part 9' so that it has the same height as the socket 30. Whenthe boom is in its fully extended. position as shown in FIGURES III andIV, a pivot pin; 33 extends down through the socket' 30 and throughaligned tubular sockets 34 and 35 in the upper plate 25 and in the lowerplates 23'and 26 vrespectively to connect the two boom parts together.The outer boom part 9 is free to slew about the pivot pin 33 but it can'be bolted in any one of three positions in which it extends straightforwards in alignment with the inner boom part '4 as shown in FIGURE Vor at anangle of 25 to one end of the outer part 9 is also secured bymeans of the bolts 36, 37 and 38 which now pass through ,holes'. 5 2,

53 and 54 respectively in the plate 23 and in a strengthening plate 55immediately beneath the plate 23 .at the inner' end of the boom part 4.The outer boom part 9 cannot of course slew from side t'o's iderelatively to the innerpart 4 when'it is retracted in this way. Thisretraction of the boom is-fullydescribed and claimed .in our cop'endingapplication No. 304,586, filed August 26, 1962.

The construction of the boom and the mounting of the bucket 16 on theend of the arm 10 enable the excavator 'to be very adaptable and to beused for a wide variety of ,functions: If the bucket is mounted as shownin FIGURES I and II, the machine is ready for use as a back-actor ordrag shovel. If the two boom parts are locked in the straight aheadpositions as illustrated in FIGURE V, a trench can be dug in line withthe central longitudinal lineof the chassis. the super-structu-re'l isslewed to one side or the other through 25, for example clockwise asseen from above and as shown in FIGURE II, and the outer boom part 9 isslewed in an anti-clockwise direction relatively to venient toretractthe outer boom part 9 within the inner part 4 to reduce thelengthof the boom. With the boom retracted in this way, the excavator isalso ready for transporting a We'clairn: v I t I 1. In an excavator ofthe kind having a chassis, asu- J perstructure, turntable meansrotatablymounting said fixed in the straight ahead position shown in FIGURE 7 Vby means of three bolts 36, 37 and, 38 which pass through sockets in theinner end of the outer boom part 9 and through holes 39, 40 and '41respectively formed in the bottom plates 23 and 26 of the inner boompart 4. When the outer boom part 9 is slewed to, the left, as seen fromabove and in the direction in which the boom points, the bolts 37 and 38are transferred to holes 42 and 43 in the bottom plates 23 and 26 andthe bolts 36 are replaced by a pair of bolts 44 and 45 which passthrough tubular sockets 46 at the extreme inner 'end of the outer boompart 9 and through sockets -47 and 48 respectively in one side wall ofthe housing 27. Similarly, when the outer boom part is slewed in theother direction the bolts 37 and 38 are transferred to holes 42 and 49'in the base plates23 and 26 and the bolts' superstructure on saidchassis for'slewing movements relative thereto, a boom, means pivot-allymounting ,said boomon-said superstructure, a digging arm, meanspivotally mounting said digging arm on said boonnand a digging bucketmounted on said digging arm; the improved arm' rocking means and boomwhich comprises an inner boom part mounted on said superstructure, anouter boom part carrying said digging arm, a hydraulic ram connectedbetween said outer boom part and digging arm to rock said arm on saidboom, means connecting a said inner and outer boom parts togetherwhereby. said said outer boom parts are aligned with each otherso thatthe. axis of said boom is straight as seen from above,

44 and 45 pass through the sockets 46 anduthrough sockets 50 and 51respectively in the other side wall ofend -from.the bottom plates .orside walls of the housing 7 27 and removing the pivot pin 33. The outerboom part 9 is then retracted through the housing 27 until the socket 31is aligned with the sockets 34 and 35. It is.

then secured in position by reinse'rting the pivot pin33 27 and throughthe 599149; 31 in thepart 9. The inner through the tubular sockets 34and 35 in the housing said second position being defined when said outerboom part is set at an angle to one side as seen from above to saidinner boom part,'saicl third position being defined when said outer boompart is set at an angle to the other side as seen from above to saidinner boom part; and means forffixing said outer boom part in any one ofsaid three positions. V

2. An excavator according to claim 1, in which said means for pivotallyconnecting said boom parts together comprises tubular sockets in saidinner and outer boom parts and a pivot pin passing through said tubularsockets.

3. An excavator according to claim 2, in which said means for fixingsaid outer boompart in each of said three positions comprises holes inboth of said boom parts, at least one hole in each boom part beingpositioned to register with at least one hole in the other boom partwhen said outer boom occupies each of its said three positions, and boltmeans passing through said registering holes. I v 3 t 4, An "excavatoraccording to claim 1, in which the inner boom-partcomprises two closedbox sections ar- However, if

ranged side by side, a bottom plate extending between two said boxsections, a top plate extending between said two box sections at theouter end thereof to define a housing adapted to receive the inner endof said outer boom part, said means for fixing said outer boom part ineach of its three positions being provided within said housing.

5. In an excavator of the kind having a chassis, a superstructure,turntable means rotatably mounting said superstructure on said chassisfor slewing movements relative thereto, a boom, means pivotally mountingsaid boom on said superstructure, a digging arm, means pivotallymounting said digging arm on said boom, and a digging bucket mounted onsaid digging arm; the improved arm rocking means and boom whichcomprises an inner boom part mounted on said superstructure, an outerboom part carrying said digging arm, a hydraulic rain connected betweensaid outer boom part and said digging arm to rock said arm on said boom,and means for fixing said inner and outer boom parts to each other inany one of three positions; said positions including a first positiondefined when said inner and said outer boom parts are aligned with eachother so that the axis of said boom is straight as seen from above, asecond position defined when said outer boom part is set at an angle toone side as seen from above to said inner boom part, and a thirdposition defined when said outer boom part is set at an angle to theother side as seen from above to said inner boom part.

References Cited by the Examiner UNITED STATES PATENTS 3,027,026 3/62Conquet 2l4l38 FOREIGN PATENTS 556,535 2/57 Italy.

HUGO O. SCHULZ, Primary Examiner.

1. IN AN EXCAVATOR OF THE KIND HAVING A CHASSIS, A SUPERSTRUCTURE,TURNTABLE MEANS ROTATABLY MOUNTING SAID SUPERSTRUCTURE ON SAID CHASSISFOR SLEWING MOVEMENTS RELATIVE THERETO, A BOOM, MEANS PIVOTALLY MOUNTINGSAID BOOM ON SAID SUPERSTRUCTURE, A DIGGING ARM, MEANS PIVOTALLYMOUNTING SAID DIGGING ARM ON SAID BOOM, AND A DIGGING BUCKET MOUNTED ONSAID DIGGING ARM; THE IMPROVED ARM ROCKING MEANS AND BOOM WHICHCOMPRISES AN INNER BOOM PART MOUNTED ON SAID SUPERSTRUCTURE, AN OUTERBOOM CARRYING SAID DIGGING ARM, A HYDRAULIC RAM CONNECTED BETWEEN SAIDOUTER BOOM PART AND DIGGING ARM TO ROCK SAID ARM ON SAID BOOM, MEANSCONNECTIN G SAID INNER AND OUTER BOOM PARTS TOGETHER WHEREBY SAID OUTERBOOM PART IS ADAPTED TO SLEW FROM SIDE TO SIDE RELATIVELY TO SAID INNERBOOM PART BETWEEN THREE POSITIONS; SAID FIRST POSITION BEING DEFINEDWHEN SAID INNER AND SAID OUTER BOOM PARTS ARE ALIGNED WITH EACH OTHER SOTHAT THE AXIS OF SAID BOOM IS STRAIGHT AS SEEN FROM ABOVE, SAID SECONDPOSITION BEIND DEFINED WHEN SAID OUTER BOOM PART IS SET AT AN ANGLE TOONE SIDE AS SEEN FROM ABOVE TO SAID INNER BOOM PART, SAID THIRD POSITIONBEIND DEFINED WHEN SAID OUTER BOOM PART IS SET AT AN ANGLE TO THE OTHERSIDE AS SEEN FROM ABOVE TO SAID INNER BOOM PART; AND MEANS FOR FIXINGSAID OUTER BOOM PART IN ANY ONE OF SAID THREE POSITIONS.